Energy storage systems often include, among other things, semiconductor devices. Switching operations of these semiconductor devices perform non-instantaneous transitions of the voltage and current resulting in switching losses in the semiconductor devices and formation of ripple currents.
Certain energy storage systems include power converters that operable in buck and boost modes in connection with the charging and discharging of energy storage devices used in the system. Due to the switching nature of such converters in the energy storage systems, the current flowing through an inductor and consequently a capacitor used as an energy storage device in the system will increase or decrease based on the present switching state of the semiconductor devices included in the system to form a ripple current. The ripple current introduces additional losses in the energy storage systems due to their parasitic series resistance. These additional loses increase the system loses and can shorten the lifetime of energy storage devices.
The ripple current can be reduced to a desired level by increasing the value of the inductor L and/or increasing the switching frequency of the semiconductor devices used in the energy storage system. Unfortunately, increasing the inductance increases the size, weight and cost of the power converter in the energy storage system, as well as possibly increasing the losses within inductors in the system. Increasing the switching frequency will proportionally increase the switching losses, as well as reduce the life of the semiconductor devices.